Previous work has indicated that inner-city women are significantly more likely to use crack/cocaine than any other drug, and are also more likely to use crack/cocaine than men across current use and lifetime heaviest use (Lejuez, et al., in press). In addition, previous results suggest that impulsivity may underlie the choice of women to choose crack/cocaine when considered over their lifetime. These findings of elevated crack use with women are surprising and problematic as crack/cocaine use, more so than other drugs, has been related to a number of serious helath-compromising behaviors including risky sexual beheavior and contraction of HIV. Building on previous research, this cross-sectional, exploratory study of 240.drug users, currently enrolled in residential substnace abuse treatment, aims to replicate the previous findings indicating that females evidence greater use (current and lifetime heaviest) of crack/cocaine compared to males. In addition, this study will examine role of impulsivity as a mediator in the relationship between gender and crack/cocaine drug use. Because impulsivity has been identified as a multidimensional construct, it will be measured in a multi-method manner using both self-report and behavioral tasks in order to address how specific components of impulsivity are related to drug choice. Further this study plans to expand upon previous research by exploring the environmental context surrounding drug use and the individual's response to that context. To accomplish this goal, both self-report and behavioral tasks will be used to assess the social context variables of drug availability within a user's social networks and means of drug obtainment, as well as the social cognitive variables of sensitivity to ostracism, need for closure, and tendency to conform to the drug use of those in one's network. The Social Action Theory (SAT) will be used as a framework to guide the work. The SAT elaborates upon existing social-cognitive models. Specifically, the application of SAT to drug choice will encompass 3 major domains: 1) environmental context, 2) self- regulation capacities of the individual and, 3) internal-affective states that influence self-regulation. In terms of public health, this research has the potential to inform and aid in the development of drug treatment and intervention strategies specifically tailored to inner-city crack/cocaine abusing women, a currently underserved and poorly understood population, with the goal of limiting resulting consequences especially linked to this drug including incarceration and HIV infection. -